1. Field of the Invention
This invention relates to a light-emitting device and a method for manufacturing the same, more particularly to a light-emitting device that includes an epitaxial structure having an indium-containing oxide, and a method for manufacturing the same.
2. Description of the Related Art
Referring to FIG. 1, a conventional light-emitting device includes a substrate 10, a first cladding layer 11, a light-emitting layer 12, a second cladding layer 13, and an electrode unit 14.
Normally, the first cladding layer 11 is made of an n-type semiconductor material, such as an n-type gallium nitride. The second cladding layer 13 is made of a p-type semiconductor material, such as a p-type gallium nitride. The light-emitting layer 12 is sandwiched between the first and second cladding layers 11, 13, and can emit light when supplied with external electricity.
The electrode unit 14 is made of a conductive material, such as a metal or an alloy, and includes a first electrode 141 disposed on the first cladding layer 11, and a second electrode 142 disposed on the second cladding layer 13. When the external electricity is applied to the first and second electrodes 141, 142, it is transmitted to the light-emitting layer 12 through the first and second cladding layers 11, 13.
In order to evenly and laterally distribute the electric current from the second electrode 142 to the second cladding layer 13, and in order to reduce a contact resistance between a conductor (i.e., the second electrode 142) and a semiconductor (i.e., the second cladding layer 23), a transparent conductive layer (not shown) is usually formed on an entire upper surface 131 of the second cladding layer 13. Normally, the transparent conductive layer is formed by sputtering deposition of an indium tin oxide (ITO) material. However, the sputtered indium tin oxide layer has poor adhesion to the second cladding layer 13, which may result in an unduly large contact resistance between the sputtered ITO material layer and the second cladding layer 13. As such, the working voltage of the conventional light-emitting device is relatively high.